Manufacturing method of display device providing light emission on bezel region

ABSTRACT

A display device includes a first substrate, a first emission layer disposed on the first substrate and emitted by a top emission type, a second substrate facing the first substrate and covering the first substrate, and a second emission layer disposed under the second substrate and emitted by a bottom emission type, wherein a portion of the first emission layer and a portion of the second emission layer.

This application is a divisional of U.S. patent application Ser. No.14/933,293, filed on Nov. 5, 2015, which claims priority to KoreanPatent Application No. 10-2015-0058111 filed on Apr. 24, 2015, and allthe benefits accruing therefrom under 35 U.S.C. § 119, the content ofwhich in its entirety is incorporated herein by reference.

BACKGROUND 1. Field

The invention relates to a display device and a manufacturing methodthereof.

2. Description of the Related Art

A display device mainly uses a flat panel display, such as a liquidcrystal display, an organic light emitting device, or a plasma display,for example. Particularly, an organic light emitting device includes twoelectrodes and an organic emission layer interposed therebetween,electrons injected from one electrode and holes injected from the otherelectrode are combined in the organic emission layer to form excitons,and the excitons release energy to emit light.

The display device includes a light emission region and a bezel regionas a non-light emission region surrounding the light emission region. Asignal processing circuit to drive the plurality of pixels is positionedin the display area and an edge of an encapsulation layer to protect theplurality of pixels is positioned in the bezel region. Efforts tominimize the bezel region in order to maximize the light emission regionare being further researched.

SUMMARY

When bending a window to minimize a bezel region, a dead space is stillexists and a reliability of an edge of an encapsulation layerdeteriorates.

The invention provides a display device for the removal of a non-lightemitting region, along with a manufacturing method thereof.

A display device according to an exemplary embodiment of the inventionincludes a first substrate, a first emission layer disposed on the firstsubstrate and emitted by a top emission type, a second substrate facingthe first substrate and covering the first substrate, and a secondemission layer disposed under the second substrate and emitted by abottom emission type, wherein the portion of the first emission layerand the portion of the second emission layer overlap each other.

In an exemplary embodiment, the first substrate may include a firstcenter portion and a first outer portion enclosing the first centerportion, the second substrate may include a second center portion, asecond outer portion enclosing the second center portion, and anoverlapping portion between the second center portion and the secondouter portion, and the second emission layer may be disposed under thesecond outer portion and the overlapping portion.

In an exemplary embodiment, the first substrate and second substrate mayrespectively include thin glasses having a thickness of about 50micrometers (μm) to about 100 μm.

In an exemplary embodiment, the first substrate and the second substratemay be respectively chemical tempered glasses including a potassiumfactor.

In an exemplary embodiment, the overlapping portion and the first outerportion may overlap each other.

In an exemplary embodiment, the portion of the first emission layerpositioned at the first outer portion and the portion of the secondemission layer positioned at the overlapping portion may overlap eachother.

In an exemplary embodiment, a first encapsulation layer covering thefirst emission layer, a second encapsulation layer covering the secondemission layer and the second substrate, and an adhesive layer adheringthe first encapsulation layer and the second encapsulation layer to eachother may be further included.

In an exemplary embodiment, the second center portion of the secondsubstrate may contact the second encapsulation layer.

In an exemplary embodiment, the thickness of the adhesive layerpositioned in the second center portion of the second substrate may belarger than the thickness of the adhesive layer positioned in the secondouter portion and the overlapping portion of the second substrate.

In an exemplary embodiment, the first emission layer may include aplurality of first pixels, the second emission layer may include aplurality of second pixels, and a boundary portion interval serving asan interval between a second outermost pixel, which is the outermostpixel among the plurality of second pixels, and the first pixel closestto the second outermost pixel among the plurality of first pixels on aplane surface may be substantially the same as the center portioninterval serving as the interval between the adjacent first pixels amongthe plurality of first pixels.

In an exemplary embodiment, the first pixel may only be positioned inthe first center portion.

In an exemplary embodiment, the first pixel may be positioned at thefirst center portion and the first outer portion.

In an exemplary embodiment, the first pixel may include a first drivingtransistor disposed on the first substrate and a first organic lightemitting diode connected to the first driving transistor, the secondpixel may include a second driving transistor disposed on the secondsubstrate and a second organic light emitting diode connected to thesecond driving transistor, and the light emitted from the first organiclight emitting diode and the second organic light emitting diode maypass through the second substrate to be irradiated.

In an exemplary embodiment, a polarizer disposed on the second substratemay be further included.

In an exemplary embodiment, the polarizer may include a light blockingmember that is disposed on the second substrate and has a plurality oflight blocking openings, and a color filter disposed in the plurality oflight blocking openings.

In an exemplary embodiment, a first hard coating layer disposed on thepolarizer may be further included.

In an exemplary embodiment, a touch sensor disposed on the first hardcoating layer may be further included.

In an exemplary embodiment, a second hard coating layer disposed on thetouch sensor may be further included.

A manufacturing method of a display device according to an exemplaryembodiment of the invention includes forming a first emission layeremitting light by a top emission type on a first substrate, forming afirst encapsulation layer covering the first emission layer, forming asecond emission layer emitting the light by a bottom emission type onthe second outer portion and the overlapping portion of the secondsubstrate, covering a second encapsulation layer covering the secondemission layer, and turning the second substrate and interposing anadhesive layer between the first encapsulation layer and the secondencapsulation layer to adhere the first encapsulation layer and thesecond encapsulation layer, wherein the portion of the first emissionlayer and the portion of the second emission layer overlap each other.

In an exemplary embodiment, the method may further include chemicallyreinforcing the first substrate and the second substrate

In an exemplary embodiment, the first substrate and second substrate mayinclude a thin glass having a thickness of about 50 micrometers (μm) toabout 100 μm, respectively.

In an exemplary embodiment, the first substrate may include a firstcenter portion and a first outer portion enclosing the first centerportion, the second substrate may include a second center portion, asecond outer portion enclosing the second center portion, and anoverlapping portion between the second center portion and the secondouter portion, and the second emission layer may be disposed under thesecond outer portion and the overlapping portion.

In an exemplary embodiment, the overlapping portion and the first outerportion may overlap each other.

In an exemplary embodiment, the portion of the first emission layerpositioned at the first outer portion and the portion of the secondemission layer positioned at the overlapping portion may overlap eachother.

In an exemplary embodiment, the method may further include forming apolarization layer on the second substrate and forming a first hardcoating layer on the polarization layer.

In an exemplary embodiment, the method may further include forming atouch sensor on the first hard coating layer and forming a second hardcoating layer on the touch sensor.

According to an exemplary embodiment of the invention, the second centerportion of the second substrate is used as a window for the top emissionand the second outer portion, and the overlapping portion of the secondsubstrate is simultaneously used as the substrate for the bottomemission, thereby maximizing the emission region.

Also, the portion of the first emission layer of the first substrate andthe portion of the second emission layer of the second substrate overlapeach other, and the center portion interval between the first pixels orthe second pixels and the boundary portion interval between the firstpixel and the second pixel are provided to be substantially the same inorder to not recognize the boundary portion between the first pixel andthe second pixel, such that the first emission layer of the top emissionand the second emission layer of the bottom emission may be notdistinguished. Accordingly, the display quality may be improved.

Also, the first substrate and the second substrate including thin glassare chemically reinforced, or the first hard coating layer and thesecond hard coating layer are disposed on the second substrate, therebysimultaneously satisfying the flexibility and the hardness of thedisplay device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other exemplary embodiments, advantages and features ofthis disclosure will become more apparent by describing in furtherdetail exemplary embodiments thereof with reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic top plan view of a display device according to anexemplary embodiment of the invention.

FIG. 2 is a schematic cross-sectional view of a display device accordingto an exemplary embodiment of the invention.

FIG. 3 is an enlarged cross-sectional view of one end portion of FIG. 2.

FIG. 4 is an enlarged top plan view of a portion A of FIG. 1.

FIG. 5 is an equivalent circuit diagram of one pixel of a display deviceaccording to an exemplary embodiment of the invention.

FIG. 6 is an enlarged top plan view of a portion B of FIG. 3.

FIGS. 7, 8 and 9 are cross-sectional views sequentially showing amanufacturing method of a display device according to an exemplaryembodiment of the invention.

FIG. 10 is a detailed cross-sectional view of a display device accordingto another exemplary embodiment of the invention.

FIG. 11 is an enlarged top plan view of a portion B of FIG. 10.

DETAILED DESCRIPTION

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. As those skilled in the art would realize, thedescribed embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the invention.

The drawings and description are to be regarded as illustrative innature and not restrictive. Like reference numerals designate likeelements throughout the specification.

Further, since sizes and thicknesses of constituent members shown in theaccompanying drawings are arbitrarily given for better understanding andease of description, the invention is not limited thereto. In thedrawings, the thickness of layers, films, panels, regions, etc., areexaggerated for clarity. In the drawings, for better understanding andease of description, the thicknesses of some layers and areas areexaggerated.

In the specification, unless explicitly described to the contrary, theword “comprise” and variations such as “comprises” or “comprising” willbe understood to imply the inclusion of stated elements but not theexclusion of any other elements. In addition, it will be understood thatwhen an element such as a layer, film, region, or substrate is referredto as being “on” another element, it can be directly on the otherelement or intervening elements may also be present. In contrast, whenan element is referred to as being “directly on” another element, thereare no intervening elements present. Further, in the specification, theword “on” means positioning on or below the object portion, and does notnecessarily mean positioning on the upper side of the object portionbased on a direction of gravity.

Further, in the specification, the word “on a flat surface” means whenan object portion is viewed from above, and the word “on a crosssection” means when a cross section taken by vertically cutting anobject portion is viewed from the side.

Further, the invention is not limited to the number of thin filmtransistors TFT and capacitors illustrated in the accompanying drawings,and the organic light emitting diode display may include a plurality ofthin film transistors and one or more capacitors in one pixel, and aseparate wire may be further provided or a known wire may be omitted toprovide various structures. Here, the pixel means a minimum unitdisplaying an image, and the display device displays an image through aplurality of pixels.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

Now, a display device according to an exemplary embodiment of theinvention will be described in detail with reference to the accompanyingdrawings.

FIG. 1 is a schematic top plan view of a display device according to anexemplary embodiment of the invention, FIG. 2 is a schematiccross-sectional view of a display device according to an exemplaryembodiment of the invention, FIG. 3 is an enlarged cross-sectional viewof one end portion of FIG. 2, FIG. 4 is an enlarged top plan view of aportion A of FIG. 1, FIG. 5 is an equivalent circuit diagram of onepixel of a display device according to an exemplary embodiment of theinvention, and FIG. 6 is an enlarged top plan view of a portion B ofFIG. 3.

First, as shown in FIGS. 1 and 2, a display device according to anexemplary embodiment of the invention includes a first substrate 110, afirst emission layer 120 disposed on the first substrate 110, a firstencapsulation layer 130 covering the first emission layer 120, a secondsubstrate 210 facing the first substrate 110 and covering the firstsubstrate 110, a second emission layer 220 disposed under the secondsubstrate 210, a second encapsulation layer 230 covering the secondemission layer 220 and the second substrate 210, an adhesive layer 300interposed between the first encapsulation layer 130 and the secondencapsulation layer 230 and adhering the first encapsulation layer 130and the second encapsulation layer 230.

In an exemplary embodiment, the first substrate 110 may include a thinglass having a thickness of about 50 micrometers (μm) to about 100 μm,for example. In the case that the first substrate 110 includes a polymersuch as PI to improve flexibility, when hardening the polymer, manyimpurities are generated such that there are a large number of processdefects, and the surface charges are increased such that staticelectricity is generated, thereby requiring the management of foreignmatter. However, when the first substrate 110 includes thin glass, theimpurities and static electricity are not generated such that theadditional management of foreign matter is not required. Also, when thefirst substrate 110 includes thin glass, the first substrate 110 isstronger than when including a polyimide such that the impactreliability is also high.

The first substrate 110 includes a first center portion PA1 and a firstouter portion PB1 enclosing the first center portion PA1. This firstsubstrate 110 may be a chemical tempered glass. Chemical tempered glassis a glass with a surface hardness that is enhanced by replacing asodium factor as one basic component of the glass composition with apotassium factor to generate a compress stress in the surface of theglass.

As shown in FIG. 3, first emission layer 120 of the first substrate 110is disposed in a position corresponding to the first center portion PA1and first outer portion PB1. The first emission layer 120 includes aplurality of first pixels PX1 emitting light through a top surface. Theplurality of first pixels PX1 is disposed at one position correspondingto the first center portion PA1.

The first encapsulation layer 130 is a thin film encapsulation layer inwhich an organic layer and an inorganic layer are alternately depositedand may be transparent.

The second substrate 210 has a larger area than the first substrate 110and covers the entire first substrate 110. The second substrate 210includes a second center portion PA2 overlapping the first centerportion PA1 of the first substrate 110, a second outer portion PB2 thatdoes not overlap the first substrate 110, and an overlapping portion PCoverlapping the first outer portion PB1 of the first substrate 110.

In an exemplary embodiment, the second substrate 210 may include thinglass having a thickness of about 50 μm to about 100 μm, for example. Inthe case that the second substrate 210 includes a polymer such as PI toimprove flexibility, when hardening the polymer, many impurities aregenerated such that there is a large number of process defects, and thesurface charges are increased such that static electricity is generated,thereby requiring the management of foreign matter. However, when thefirst substrate 210 includes thin glass, the impurities and staticelectricity are not generated such that the additional management offoreign matter is not required. Also, when the second substrate 210includes thin glass, the first substrate 110 is stronger than whenincluding a polyimide, such that the impact reliability is also high.

The second substrate 210 may be chemical tempered glass including thepotassium factor. Chemical tempered glass is thinner than generaltempered glass and is equal to or greater than 1.7 times stronger, andthere is no shrinkage or warping phenomena caused by the process.

The second emission layer 220 is disposed at a position corresponding tothe second outer portion PB2 and the overlapping portion PC of thesecond substrate 210. The second emission layer 220 includes a pluralityof second pixels PX2 emitting light to a rear surface through the secondsubstrate 210. The plurality of second pixels PX2 is disposed at aposition corresponding to the second outer portion PB2 and theoverlapping portion PC.

The second encapsulation layer 230 covers the second emission layer 220at the position corresponding to the second outer portion PB2 and theoverlapping portion PC of the second substrate 210, but directlycontacts the surface of the second center portion PA2 at the positioncorresponding to the second center portion PA2 of the second substrate210. The second encapsulation layer 230 is a thin film encapsulationlayer in which an organic layer and an inorganic layer are alternatelydeposited and may be transparent.

In an exemplary embodiment, the adhesive layer 300 as an optically clearadhesive (“OCA”) functions like glass with equal to or greater thanabout 97 percent (%) light transmittance and simultaneously hasadhesiveness, for example.

A light L1 generated from the first emission layer 120 is irradiated tothe top surface and passes the second center portion PA2 of the secondsubstrate 210, and a light L2 generated from the second emission layer220 is irradiated to the rear surface and passes the second outerportion PB2 and the overlapping portion PC of the second substrate 210.Accordingly, the light passes through all of the second center portionPA2, the second outer portion PB2, and the overlapping portion PC of thesecond substrate 210 such that the non-light emitting region does notexist in the second substrate 210.

As described above, the second center portion PA2 of the secondsubstrate 210 is used as a window of the top emission, and the secondouter portion PB2 and the overlapping portion PC of the second substrate210 are simultaneously used as the substrate of the bottom emission,thereby maximizing the emission region.

The overlapping portion PC of the second substrate 210 and the firstouter portion PB1 of the first substrate 110 overlap each other.Accordingly, a portion of the first emission layer 120 and a portion ofthe second emission layer 220 overlap each other. In this case, thefirst pixel PX1 is not disposed in the first emission layer 120 of theposition corresponding to the first outer portion PB1.

As shown in FIGS. 3 and 4, when an interval between the adjacent firstpixels PX1 among the plurality of first pixels PX1 and the intervalbetween the adjacent second pixel PX2 among the plurality of secondpixels PX2 are referred to as a center portion interval d1 x and d1 y,and the interval between the second outermost pixel PT2, which is theoutermost positioned pixel among the plurality of second pixels PX2, andthe first adjacent pixel PT1, which is closest to the second outermostpixel PT2 among the plurality of first pixels PX1 on the plane surface,is referred to as a boundary portion interval d2 x and d2 y, the centerportion interval d1 x and d1 y and the boundary portion interval d2 xand d2 y may be substantially the same.

In detail, a transverse boundary portion interval d2 x between the firstadjacent pixel PT1 and the second outermost pixel PT2 closest thereto inthe horizontal direction on the plane surface is substantially the sameas a transverse center portion interval d1 x of a horizontal directioninterval between the first pixels PX1 or the second pixels PX2. Also, alongitudinal boundary portion interval d2 y between the first adjacentpixel PT1 and the second outermost pixel PT2 closest thereto in thevertical direction on the plane surface is substantially the same as thecenter portion interval d1 y of the vertical direction interval betweenthe first pixels PX1 or the second pixels PX2.

As described above, by forming the center portion intervals d1 x and d1y between the first pixels PX1 or the second pixels PX2 and the boundaryportion intervals d2 x and d2 y between the first pixel PX1 and thesecond pixel PX2 to be substantially the same as each other, theboundary portion between the first pixel PX1 and the second pixel PX2positioned at different substrates is not recognized, and thereby thefirst emission layer 120 of the top emission and the second emissionlayer 220 of the bottom emission cannot be distinguished from eachother. Accordingly, the display quality may be improved.

Also, by forming the luminance of the first pixel PX1 and the luminanceof the second pixel PX2 to be the same as each other, the boundaryportion between the first pixel PX1 and the second pixel PX2 is notrecognized such that the display quality may be improved.

In addition, the first encapsulation layer 130 and the secondencapsulation layer 230 are transparent such that the overlappingportion PC is not recognized even though the first substrate 110 and thesecond substrate 210 partially overlap, thereby improving the displayquality.

Next, the detailed structure of the first emission layer 120 and thesecond emission layer 220 will be described with reference to FIGS. 5and 6. In this case, the structure will be described regarding thedriving transistor, since the switching transistor has substantially thesame stack structure as that of the driving transistors, and thus aduplicate description thereof will be omitted.

FIG. 5 is an equivalent circuit diagram of one pixel of a display deviceaccording to an exemplary embodiment of the invention.

As shown in FIG. 5, a display device according to an exemplaryembodiment of the invention includes a plurality of signal lines 21, 71,and 72, and a plurality of pixels PX connected to the plurality ofsignal lines and arranged in an approximate matrix type. The pluralityof pixels PX includes a first pixel PX1 (refer to FIG. 6) in which thefirst emission layer 120 (refer to FIG. 6) is disposed and a secondpixel PX2 in which the second emission layer 220 (refer to FIG. 6) isdisposed.

The signal lines 21, 71, and 72 include a plurality of scan lines 21transmitting a scan signal Sn, a plurality of data lines 71 crossing thescan lines 21 and transmitting a data signal Dm, and a plurality ofdriving voltage lines 72 transmitting a driving voltage ELVDD and whichare substantially parallel to the data lines 71. The gate lines 21extend substantially parallel to one another in a row direction, and thedata lines 71 and the driving voltage lines 72 extend substantiallyparallel to one another in a column direction.

Each pixel PX includes a plurality of transistors T1 and T2 respectivelyconnected to the plurality of signal lines 21, 71, and 72, a storagecapacitor Cst, and an organic light emitting diode OLD.

The transistors T1 and T2 include a switching transistor T1 connected tothe data line 71, and a driving transistor T2 connected to the organiclight emitting diode OLD. The driving transistor T2 includes a firstdriving transistor T21 (refer to FIG. 6) in which the first emissionlayer 120 is disposed and a second driving transistor T22 (refer to FIG.6) in which the second emission layer 220 is disposed.

The switching transistor T1 includes a control terminal, an inputterminal, and an output terminal, and the control terminal thereof isconnected to the scan line 21, the input terminal thereof is connectedto the data line 71, and the output terminal thereof is connected to thedriving transistor T2. The switching transistor T1 transmits the datasignal Dm applied to the data line 71 to the driving transistor T2 inresponse to the scan signal Sn applied to the scan line 21.

The driving transistor T2 also includes a control terminal, an inputterminal, and an output terminal, and the control terminal thereof isconnected to the switching transistor T1, the input terminal thereof isconnected to the driving voltage line 72, and the output terminalthereof is connected to the organic light emitting diode OLD. Thedriving transistor T2 allows a driving current Id, which has a levelvarying according to a voltage applied between the control terminal andthe output terminal, to flow.

The storage capacitor Cst is connected between the control terminal andthe input terminal of the driving transistor T2. The storage capacitorCst charges the data signal applied to the control terminal of thedriving transistor T2 and maintains the data signal even after theswitching transistor T1 is turned off.

The organic light emitting diode OLD includes an anode that is connectedto the output terminal of the driving transistor T2, and a cathode thatis connected to the common voltage ELVSS. The organic light emittingdiode OLD emits light with an intensity varying according to the drivingcurrent Id of the driving transistor T2, thereby displaying an image.The organic light emitting diode OLD includes a first organic lightemitting diode OLD1 (refer to FIG. 6) in which the first emission layer120 is disposed and a second organic light emitting diode OLD2 (refer toFIG. 6) in which the second emission layer 220 is disposed.

In an exemplary embodiment, the switching transistor T1 and the drivingtransistor T2 may be an n-channel field effect transistor (“FET”) or ap-channel FET. In addition, a connection relationship among thetransistors T1 and T2, the storage capacitor Cst, and the organic lightemitting diode OLD may be changed.

FIG. 6 is an enlarged cross-sectional view of a portion of FIG. 3.

As shown in FIG. 6, a first buffer layer 121 is disposed on the firstsubstrate 110. The first buffer layer 120 may serve to improve acharacteristic of the polycrystalline silicon and reduce stress appliedto the semiconductor 122 disposed on the buffer 121 by blockingimpurities from the first substrate 110 and flattening the firstsubstrate 110 during a crystallization process for formingpolycrystalline silicon. In an exemplary embodiment, the first bufferlayer 121 may include silicon nitride (SiNx) or silicon oxide (SiO2),for example.

A first semiconductor 122 is disposed on the first buffer layer 121. Inan exemplary embodiment, the first semiconductor 122 may includepolysilicon or an oxide semiconductor, for example.

A first gate insulating layer 123 covering the first semiconductor 122is disposed thereon. In an exemplary embodiment, the first gateinsulating layer 123 may include silicon nitride (SiNx) or silicon oxide(SiO2), or the like, for example.

A first gate electrode G1 is disposed on the first gate insulating layer123. The first gate electrode G1 is a part of the scan line 21 andoverlaps the first semiconductor 122.

A first interlayer insulating layer 124 covering the first gateelectrode G1 is disposed thereon. In an exemplary embodiment, the firstinterlayer insulating layer 124 may include silicon nitride (SiNx) orsilicon oxide (SiO2) like the first gate insulating layer 123, forexample.

A first source electrode S1 and a first drain electrode D1 are disposedon the first interlayer insulating layer 124. The first source electrodeS1 and the first drain electrode D1 are respectively connected to thesource region and the drain region of the first semiconductor 122. Thefirst gate electrode G1, the first source electrode S1, and the firstdrain electrode D1 provide a first driving transistor T21.

A first passivation layer 125 covering the first source electrode S1 andthe first drain electrode D1 is disposed thereon.

In an exemplary embodiment, a first pixel electrode 127 including areflective conductive material such as lithium (Li), calcium (Ca),lithium fluoride/calcium (LiF/Ca), lithium fluoride/aluminum (LiF/Al),aluminum (Al), silver (Ag), magnesium (Mg), or gold (Au) is disposed onthe first passivation layer 125. The first pixel electrode 127 iselectrically connected to the first drain electrode D1 of the firstdriving transistor T21 through the contact hole 125 a defined in thepassivation layer 125, thereby being an anode of the first organic lightemitting diode OLD1.

A first partition 126 is disposed on the first passivation layer 125 andthe edge of the first pixel electrode 127. The first partition 126 has afirst pixel opening 126 a exposing the first pixel electrode 127. In anexemplary embodiment, the first partition 126 may be provided to includea resin, such as polyacrylates or polyimides, and a silica-basedinorganic material, or the like.

The first organic emission layer 128 is disposed in the first pixelopening 126 a of the first partition 126. In an exemplary embodiment,the first organic emission layer 128 is disposed in multiple layersincluding one or more of a light emission layer, a hole injection layer(“HIL”), a hole transporting layer (“HTL”), an electron transportinglayer (“ETL”), and an electron injection layer (“EIL”). When the firstorganic light emission layer 128 includes all of the light emissionlayer, the HIL, the HTL, the ETL, and the EIL, the HIL is positioned onthe first pixel electrode 127, which is the anode, and the HTL, thelight emission layer, the ETL, and the EIL are sequentially stacked onthe HIL.

In an exemplary embodiment, a first common electrode 129 including atransparent conductive material such as indium tin oxide (“ITO”), indiumzinc oxide (“IZO”), zinc oxide (ZnO), or indium oxide (In2O3) isdisposed on the first partition 126 and the first organic emission layer128. The first common electrode 129 becomes a cathode of the firstorganic light emitting diode OLD. The first pixel electrode 127, thefirst organic emission layer 128, and the first common electrode 129together provide a first organic light emitting diode OLD1. The firstorganic light emitting diode OLD1 includes the first pixel electrode 127including a reflection conductive material and the first commonelectrode 129 including the transparent conductive material such thatthe light L1 emitted from the first organic emission layer 128 isreflected on the first pixel electrode 127 and passes through the firstcommon electrode 129. Accordingly, the light L1 emitted from the firstorganic emission layer 128 passes through the second center portion PA2of the second substrate 210.

A second buffer layer 221 is disposed under the second substrate 210. Asecond semiconductor 222 is disposed on the second buffer layer 221. Asecond gate insulating layer 223 covering the second semiconductor 222is disposed on the second semiconductor 222. A second gate electrode G2is disposed on the second gate insulating layer 223. The first gateelectrode G1 is part of the scan line 21 and partially overlaps thesecond semiconductor 222.

A second interlayer insulating layer 224 covering the second gateelectrode G2 is disposed thereunder. A second source electrode S2 and asecond drain electrode D2 are disposed under the second interlayerinsulating layer 224. The second source electrode S2 and the seconddrain electrode D2 are respectively connected to the source region andthe drain region of the second semiconductor 222. The second gateelectrode G2, the second source electrode S2, and the second drainelectrode D2 provide a second driving transistor T22.

A second passivation layer 225 covering the second source electrode S2and the second drain electrode D2 is disposed thereunder.

A second pixel electrode 227 including the transparent conductivematerial is disposed under the second passivation layer 225. The secondpixel electrode 227 is electrically connected to the second drainelectrode D2 of the second driving transistor T22 through the contacthole 225 a defined in the second passivation layer 225, thereby beingthe anode of the second organic light emitting diode OLD2.

A second partition 226 is disposed on the second passivation layer 225and the edge of the second pixel electrode 227. The second partition 226has a second pixel opening 226 a exposing the first pixel electrode 127.

A second organic emission layer 228 is disposed in the second pixelopening 226 a of the second partition 226. The second organic emissionlayer 228 is disposed in multiple layers including one or more of alight emission layer, an HIL, an HTL, an ETL, and an EIL. When secondorganic emission layer 228 includes all of the light emission layer, theHIL, the HTL, the ETL, and the EIL, the HIL is positioned on the secondpixel electrode 227, which is the anode, and the HTL, the light emissionlayer, the ETL, and the EIL are sequentially stacked on the HIL.

A second common electrode 229 including the reflective conductivematerial is disposed under the second partition 226 and the secondorganic emission layer 228. The second common electrode 229 becomes thecathode of the second organic light emitting diode OLD2. The secondpixel electrode 227, the second organic emission layer 228, and thesecond common electrode 229 together provide the second organic lightemitting diode OLD2. Since the second organic light emitting diode OLD2includes a second pixel electrode 227 including the transparentconductive material and a second common electrode 229 including thereflective conductive material, the light L2 emitted from the secondorganic emission layer 228 passes through the second pixel electrode 227and is reflected by the second common electrode 229. Accordingly, thelight L2 emitted from the second organic emission layer 228 passesthrough the second outer portion PB2 and the overlapping portion PC ofthe second substrate 210.

The first pixel PX1 including the first driving transistor T21 and thefirst organic light emitting diode OLD1 is only provided at the positioncorresponding to the first center portion PA1 of the first substrate110, but is not provided at the position corresponding to the firstouter portion PB1 of the first substrate 110. Also, the second pixel PX2including the second driving transistor T22 and the second organic lightemitting diode OLD2 is provided at the position corresponding to theoverlapping portion PC and the second outer portion PB2 (refer to FIGS.1 to 3) of the second substrate 210.

Also, the transverse boundary portion interval d2 x between the firstadjacent pixel PT1 (refer to FIG. 4) and the second outermost pixel PT2(refer to FIG. 4) closest thereto in the horizontal direction on theplane surface is substantially the same as the transverse center portioninterval d1 x of the horizontal direction interval between the firstpixels PX1. As described above, by forming the center portion intervald1 x between the first pixels PX1 and the boundary portion interval d2 xbetween the first pixel PX1 and the second pixel PX2 to be substantiallythe same, the boundary portion between the first pixel PX1 and thesecond pixel PX2 is not recognized such that the first emission layer120 of the top emission and the second emission layer 220 of the bottomemission may not be distinguished from each other. Accordingly, thedisplay quality may be improved.

An adhesive layer 300 is disposed between the first encapsulation layer130 and the second encapsulation layer 230. In this case, the secondencapsulation layer 230 covering the end of the second emission layer220 covers the inclined side wall of the second emission layer 220, andthe second encapsulation layer 230 contacts the surface of the secondsubstrate 210.

Also, a polarization layer 240 to remove the reflection of the externallight is disposed on the second substrate 210. The polarization layer240 is disposed on the second substrate 210 and includes a lightblocking member 241 blocking the light and a color filter 242 isdisposed in a plurality of light blocking openings 241 a of the lightblocking member 241. In an exemplary embodiment, the light blockingmember 241 may include a metal such as chromium (Cr) or an organicmaterial, and the color filter 242 may overlap a portion of the lightblocking member 241.

A first hard coating layer 250 is disposed on the polarization layer240. In an exemplary embodiment, the first hard coating layer 250includes a siloxane-based compound, the siloxane-based compound includesany one of poly ether modified poly dimethyl siloxane or poly dimethylsiloxane of a poly ether modified hydroxyl functional group, or acombination of two or more thereof, that is, examples of thesiloxane-based compound include BYK-306 (BYK chemi agent), BYK-307,BYK-308, BYK-310, BYK-330, BYK-333, BYK-341, and BYK-344.

A touch sensor 260 is disposed on the first hard coating layer 250. Thetouch sensor 260 adhered under the second substrate 210 as an inputdevice of the display device inputs the information through a screenbeing directly contacted by a finger or a pen. The touch sensor 260 maybe a capacitive type sensing a position where a capacitance change isgenerated according to the contact on two electrodes separated from eachother.

A second hard coating layer 270 is disposed on the touch sensor 260. Inan exemplary embodiment, the second hard coating layer 270 includes asiloxane-based compound, the siloxane-based compound may include any oneamong poly ether modified poly dimethyl siloxane or a poly dimethylsiloxane of poly ether modified hydroxyl functional group, or acombination of two or more thereof, that is, examples of thesiloxane-based compound include BYK-306 (BYK chemi agent), BYK-307,BYK-308, BYK-310, BYK-330, BYK-333, BYK-341, and BYK-344.

As described above, by forming the first hard coating layer 250 and thesecond hard coating layer 270, the hardness of the second substrate 210as the glass substrate having a thin thickness of about 50 μm to about100 μm, for example, may be improved. In this case, the second hardcoating layer 270 may be omitted.

A manufacturing method of the display device according to an exemplaryembodiment of the invention will be described with reference to theaccompanying drawings.

FIGS. 7, 8, and 9 are cross-sectional views sequentially showing amanufacturing method of a display device according to an exemplaryembodiment of the invention.

First, as shown in FIG. 7, the first substrate 110 and the secondsubstrate 210 are chemically enhanced by replacing a sodium factor witha potassium factor in the first substrate 110 and second substrate 210.In an exemplary embodiment, as the chemical enhancing method, a slurryprocess using an ion exchange slurry, a dipping process enabling thereuse of a potassium nitrate salt, or a deposition process reducing amaterial and simplifying the process without a oxide-based additive or adistilled water is used, for example.

In an exemplary embodiment, the first substrate 110 and the secondsubstrate 210 include a glass, and the surface hardness thereof isenhanced by replacing a sodium factor as one of basic components of aglass composition with a potassium factor to generate a compress stressin the surface of the glass. Accordingly, by manufacturing the firstsubstrate 110 and the second substrate 220 including thin glass having athickness of about 50 μm to about 100 μm, for example, the flexibilitymay be improved and the hardness may be improved.

Next, as shown in FIG. 8, the first emission layer 120 of the topemission type is disposed on the first substrate 110. Also, the firstencapsulation layer 130 covering the first emission layer 120 isprovided.

Next, as shown in FIG. 9, the second emission layer 220 of the bottomemission type through the second substrate 210 is disposed on the secondouter portion PB2 and the overlapping portion PC of the second substrate210. Also, the second encapsulation layer 230 covering the secondemission layer 220 is provided.

Next, as shown in FIG. 2, the second substrate 210 is turned and theadhesive layer 300 is interposed between the first encapsulation layer130 and the second encapsulation layer 230 to adhere the firstencapsulation layer 130 and the second encapsulation layer 230.

In this case, the portion of the first emission layer 120 and theportion of the second emission layer 220 overlap each other. In thiscase, since the second emission layer 220 is not positioned in thesecond center portion PA2 of the second substrate 210, the thickness t1of the adhesive layer 300 positioned in the second center portion PA2 ofthe second substrate 210 may be larger than the thickness t2 of theadhesive layer positioned in the second outer portion PB2 and theoverlapping portion PC of the second substrate 210.

Also, by forming the center portion intervals d1 x (refer to FIG. 4) andd1 y (refer to FIG. 4) between the first pixels PX1 or the second pixelsPX2 and the boundary portion intervals d2 x (refer to FIG. 4) and d2 y(refer to FIG. 4) between the first pixel PX1 and the second pixel PX2to be substantially the same, the boundary portion between the firstpixel PX1 and the second pixel PX2 positioned in the differentsubstrates is not recognized such that the first emission layer 120 ofthe top emission and the second emission layer 220 of the bottomemission may not be distinguished from each other.

Also, on the second substrate 210, the polarization layer 240, the firsthard coating layer 250, the touch sensor 260, and the second hardcoating layer 270 are sequentially provided. As described above, byforming the first hard coating layer 250 and the second hard coatinglayer 270, the hardness of the second substrate 210 as a thin glasssubstrate having a thickness of about 50 μm to about 100 μm may beimproved, for example.

In the exemplary embodiment, the first pixel may not be disposed in thefirst emission layer of the position corresponding to the first outerportion, and the first pixel may be disposed in the first emission layerof the position corresponding to the first outer portion in anotherexemplary embodiment.

Next, the display device according to another exemplary embodiment ofthe invention will be described with reference to FIGS. 10 and 11.

FIG. 10 is a detailed cross-sectional view of a display device accordingto another exemplary embodiment of the invention, and FIG. 11 is anenlarged top plan view of a portion B of FIG. 10.

Another exemplary embodiment shown in FIGS. 10 and 11 is substantiallythe same as the exemplary embodiment shown in FIGS. 1 to 7, except forthe first pixel disposed in the first emission layer of the positioncorresponding to the first outer portion, such that a duplicatedescription is omitted.

As shown in FIGS. 10 and 11, in the display device according to anotherexemplary embodiment of the invention, the first pixel PX1 including thefirst driving transistor T21 and the first organic light emitting diodeOLD1 is entirely provided at the position corresponding to the firstcenter portion PA1 and the first outer portion PB1 of the firstsubstrate 110. Also, the second pixel PX2 including the second drivingtransistor T22 and the second organic light emitting diode OLD2 isprovided at the position corresponding to the overlapping portion PC andthe second outer portion PB2 of the second substrate 210.

In this case, the first organic light emitting diode OLD1 of the firstpixel PX1 provided at the position corresponding to the first outerportion PB1 includes the first pixel electrode 127 including thereflective conductive material and the first common electrode 129including the transparent conductive material such that the light L1emitted from the first organic emission layer 128 is reflected by thefirst pixel electrode 127 and passes through the first common electrode129. Accordingly, the light L1 emitted from the first organic emissionlayer 128 passes through the adhesive layer 300.

Also, the second pixel electrode 227 including the transparentconductive material is disposed under the second passivation layer 225.The second organic emission layer 228 is disposed in the second pixelopening 226 a of the second partition 226. The second common electrode229 including the transflective material is disposed under the secondpartition 226 and the second organic emission layer 228. The secondpixel electrode 227, the second organic emission layer 228, and thesecond common electrode 229 together provide the second organic lightemitting diode OLD2.

As described above, the second organic light emitting diode OLD2 of thesecond pixel PX2 provided at the position corresponding to theoverlapping portion PC of the second substrate 210 includes the secondpixel electrode 227 including the transparent conductive material andthe second common electrode 229 including the transflective materialsuch that the light L2 emitted from the second organic emission layer228 passes through the second pixel electrode 227 and reflects thesecond common electrode 229. Accordingly, the light L2 emitted from thesecond organic emission layer 228 passes through the second outerportion PB2 (refer to FIG. 10) and the overlapping portion PC of thesecond substrate 210.

Also, since the second common electrode 229 of the second pixel PX2provided at the position corresponding to the overlapping portion PC ofthe second substrate 210 includes the transflective material, the lightL1 emitted from the first organic emission layer 128 and passing throughthe adhesive layer 300 also passes through the overlapping portion PC ofthe second substrate 210.

In the overlapping portion PC of the second substrate 210, the light L1emitted from the first organic emission layer 128 and the light L2emitted from the second organic emission layer 228 are combined torealize various colors.

Also, in the exemplary embodiment, the first organic light emittingdiode is disposed on the first substrate 110, however it is not limitedthereto and a liquid crystal display may be disposed on the firstsubstrate 110 to realize the invention.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A method for manufacturing a display device, themethod comprising: forming a first emission layer which emits a light bya top emission type on a first substrate; forming a first encapsulationlayer covering the first emission layer; forming a second emission layerwhich emits a light by a bottom emission type on a second outer portionand an overlapping portion of a second substrate; covering a secondencapsulation layer covering the second emission layer; and turning thesecond substrate and interposing an adhesive layer between the firstencapsulation layer and the second encapsulation layer to adhere thefirst encapsulation layer and the second encapsulation layer, wherein aportion of the first emission layer and a portion of the second emissionlayer overlap each other, while a remaining portion of the firstemission layer and a remaining portion of the second emission layer donot overlap each other, and the first emission layer includes aplurality of organic light emitting diodes spaced apart from each otherand a plurality of organic emission layers spaced apart from each otherin the remaining portion of the first emission layer.
 2. The method ofclaim 1, further comprising: chemically reinforcing the first substrateand the second substrate.
 3. The method of claim 1, wherein: the firstsubstrate and second substrate respectively include thin glasses havinga thickness of about 50 micrometers to about 100 micrometers.
 4. Themethod of claim 1, wherein: the first substrate includes a first centerportion and a first outer portion enclosing the first center portion,the second substrate includes a second center portion, the second outerportion enclosing the second center portion, and the overlapping portionbetween the second center portion and the second outer portion, and thesecond emission layer is disposed under the second outer portion and theoverlapping portion.
 5. The method of claim 4, wherein: the overlappingportion and the first outer portion overlap each other.
 6. The method ofclaim 5, wherein: the portion of the first emission layer positioned atthe first outer portion and the portion of the second emission layerpositioned at the overlapping portion overlap each other.
 7. The methodof claim 1, further comprising: forming a polarization layer on thesecond substrate; and forming a first hard coating layer on thepolarization layer.
 8. The method of claim 7, further comprising:forming a touch sensor on the first hard coating layer; and forming asecond hard coating layer on the touch sensor.